This invention relates generally to the manufacture of kinescopes for color television receivers, or computer displays and particularly to a system for identifying envelopes having excessive offset between the panel and funnel of such a kinescope and for dispensing identification articles onto fixtures which carried rejected envelopes.
The picture tube, or kinescope, for a color television receiver, or computer display, is composed of a faceplate panel and a funnel which are fritted together along mating sealing edges. A frit material is placed on the sealing edge of either the panel or the funnel. The panel and funnel are placed together in a fixture which conveys them into an oven. The fixture includes reference members which accurately position the funnel and the panel relative to one another so that the sealing edges of the two elements properly mate along a smooth seal line. The fixture is moved by a conveyor system through the oven and the frit material vitrifies to permanently join the panel and funnel. Typically kinescopes are substantially rectangular with slightly rounded sides. The proper operation of the kinescopes requires accurate alignment of the panel and funnel along the major axis, i.e., the horizontal axis when the kinescope is in the viewing orientation. For this reason, the funnel is provided with a reference pad on the major axis. The position of the panel with respect to the reference pad is thus indicative of whether or not the panel and funnel are properly aligned. The surface of the reference pad extends beyond the surface of the panel. This extension establishes a designed offset between the funnel pad and the panel. An offset in either direction along the major axis which exceeds the designed offset by a predetermined maximum tolerance indicates an unacceptable kinescope. Because the fixture is used to align the panel and funnel an excessive offset frequently is indicative of a damaged or improperly calibrated fixture. The fixture, therefore, should be repaired or recalibrated to avoid producing additional rejects. For these reasons, there is a need for a system for automatically and accurately measuring the offset between the funnel and panel of a kinescope to verify that the offset does not exceed a predetermined maximum tolerance and for dispensing an identification article onto the fixture to identify the fixture as potentially defective. The invention fulfills this need.